I suppose technically it is wrong to say ‘reply back’ etc
But that’s like anything, why do some people say, ‘THEY DONE a test…’ when it should be ‘they did’ etc?
What is right and wrong in language is variable, because no two people will EVER have the exact same grammar.
What you have to remember is, language has never been stagnant and never will for that matter
Perhaps somewhere along the way, someone has used ‘revert back’ or something to help them remember it’s meaning and then it caught on (known as the wave effect)

In most cases, I think you’d use “reassign” without “back.” However in your example, it really makes no sense with “reassign” alone. What does it mean to reassign a defect? A defect is a personal thing in most cases. It can’t be assigned or reassigned. It is a part of you.

So in that case, you might add “back” because it hints that you are talking about a defect that belongs to something you held temporarily in your custody, like a part you were making for a car or something like that. Both sentences still sound awkward given a lack of context. But in that case, I can see using “back” to indicate that the defect is a movable thing, not something that is endemic to you.

But I would prefer another locution altogether. Something that gives more of a clue as to what is going on.

I ask because until I started working with Indian colleagues and customers I had never heard of the word “revert” being used to mean “reply”, but I find that this usage and meaning is nearly universal in Indian business communications. (To our Western ears, “revert” usually means “to set back to a prior stage”. That is, to sort of “turn back the clock” or defer to an earlier machine or process setting. We never use the word “revert” to mean “reply” or “respond”. Not.Ever.)

So in the context of Indian usage of our common language, “reassign back” seems (to me) to be a way to say what Westerners mean by “revert”. E.g., You have attempted to assign something to another worker. He attempts to reassign it someone else, who then “reassigns it back” to you, the original source. In that case, where the reassignment is not only “passing on” but “passing back”, I can understand the usage you have questioned. But only in that case.

“Reassign back” is technically correct if the person was once assigned the thing that is being reassigned to them. It’s not necessary but it’s structurally correct and adds a descriptor that indicates the person was originally or previously assigned that same thing.

Reply back and Revert back are somewhat redundant, and the word ‘back’ in those contexts is really unnecessary. Because of the redundancy, and because ‘back’ isn’t really needed with those words (Reply/Revert), I’d say they are at best stylistically and at worst technically incorrect.

If you say so, @whitenoise. But I’ve done business for many years with people from many countries in Europe and subsequently with those from several Asian countries other than India. I had never seen the “revert” usage we’re describing. My first month working with Indians (several years ago) and ever since, I see it almost daily.

@CWOTUS : Your guess is correct. I don’t use revert back, but use revert in such cases. But, I observed most of the people from HR (Human resource) department use it. A good dictionary explains the meaning of revert.

I asked this question just after I got off the call with client. The client lives in the UK and who is a native English speaker.

I said: I have reassigned the defect to you.
He replied: I have fixed the defect and reassigned it back to you.

I checked the meaning of reply here. I know it differs a lot from reply back.

My assumption for reassign is same, as “re” already conveys the idea of getting back to someone.